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#!/usr/bin/env python

"""
More TLA+ inspired coding. Using an explict step() that takes the
current state to the next state makes loop invarients easier to think
about.
"""

def str2int(s):

gulan

#!/usr/bin/env python

"""
Exercises with abstract state machines.

My remote goal is to learn how to specify systems using TLA+. I begin
by writing some simple programs is the style of those kinds of
specifications.

Any basic operator maps a before-state to an after-state. The operator

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Knowledge Representation

Say that red is a relation and b is an individual.

Is b red?

red(b).

What is red?

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"""
Arrange a program as a dictionary where the keys are program labels
and the bodies are python code. The idea is to let python do
computation, but let me define flow-control and means of program
composition.

This is a simple program, so I stick to simple Python.
"""

from collections import namedtuple

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-- from https://en.wikipedia.org/wiki/List_of_elements
-- sqlite3 periodic.db <periodic.sql

drop table if exists element;
create table element (
    number int primary key,
    symbol text not null,
    name text not null,
    period int not null,
    weight number not null);

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#!/usr/bin/env python

import fcntl
import os
import random
import sqlite3
import sys
import termios

"""

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-- The old HSK1 words. For sqlite3.

BEGIN TRANSACTION;

CREATE TABLE hsk (
   hsk_id integer primary key,
   chinese text not null,
   pinyin text not null,
   english text not null);

gulan

#!/usr/bin/env python

import sys

"""
This program demonstrates how to recognize and deal with backtracking
while processing sequential files or sequences.

A file is a sequence of runs. A run is any number of 'a', 'b' or 'x',
ending with '\n'. The file ends with a special value eof.

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#!/usr/bin/env python

"""
Convert an 'elide' file to a flashy card file.

A subject.elide file has entries of the form:

    answer
        question
        question

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module OffsetOp where
import Data.List

-- The function condense takes a list of pairs. The second value of
-- each pair denotes either a delete or skip action. The delete action
-- says that the next item in the list is to be discarded, and will
-- not appear in the result list. Skip actions do nothing.

--     1-skip 2-del 3-skip ->  1-skip 2-del